This invention relates to microwave antennas and in particular to slot radiating antennas for use on spacecraft and missiles.
It is current practice to mount microstrip patch antennas with their associated feeder networks on the outside of the space vehicle to accommodate single or multiple frequency microwave transmissions. Such a practice introducers an aerodynamic discontinuity to the fuselage thus affecting missile performance. Furthermore, the antenna elements are subjected to rapidly changing adverse environmental conditions thus reducing their reliability. Even the use of radomes which, to some extent protects antanna elements and aleviates the aerodynamic problem does not fully solve the problem. In addition, mounting microstrip patch antennas and their associated feeder networks on the outside of the vehicle requires that the antenna be a half wavelength long in the dielectic of the antenna plus the width of the microstrip feeder network. For each frequency there is a separate antenna patch and feeder network. Thus, with multiple frequencies the problem is severely compounded.
In view of the foregoing it is seen that there currently exists the need for a multifrequency antenna that can be mounted on a space vehicle without sacrificing vehicle aerodynamic integrity or subjecting antenna elements to adverse environmental conditions. It is also important that such an antenna utilize minimum axial length of the vehicle.
The present invention is directed toward satisfying that need.